/proc/mounts: Explanation & Insights

Lists the filesystems that are currently mounted on the system

The /proc/mounts file contains a list of all the filesystems currently mounted in the system. Each line in the file represents one mounted filesystem. The information it provides for each mount includes the device, mount point, filesystem type, mount options, and dump and pass options.

Why is /proc/mounts Important?

Understanding the content of this file is crucial for several reasons. It helps you to:

Understand your system's filesystem structure.
Diagnose mounting issues.
Monitor the filesystems and their options.
Understand what devices are used and their mount points.

Typical Problems That Can Be Solved

If you are experiencing problems with mounting filesystems, the /proc/mounts can provide clues to help diagnose the issue. For instance, you could encounter a situation where a device is not properly unmounted, leading to a 'device is busy' error. By examining /proc/mounts, you can verify if the device is still mounted.

Using /proc/mounts

To view the contents of the /proc/mounts file, you can use the cat command as follows:

cat /proc/mounts

Also, you can use the grep command to search for specific mount points or devices:

grep /dev/sda1 /proc/mounts

Example of /proc/mounts Content

Here is an example of what the content of /proc/mounts might look like:

/dev/sda1 / ext4 rw,relatime,errors=remount-ro 0 0
tmpfs /run tmpfs rw,nosuid,noexec,relatime,size=1638428k,mode=755 0 0
/dev/sda6 /home ext4 rw,relatime 0 0

Each field represents:

Device name
Mount point
Filesystem type
Mount options
Dump (usually 0, used by the dump backup utility)
Pass (used by the fsck command at boot time to determine the order of filesystem checks)

Conclusion

In a nutshell, /proc/mounts is a powerful tool in the hands of both Linux beginners and experts. It provides valuable information about your system's mount points and filesystems, which can be used to diagnose and solve problems, or simply to better understand how your Linux server is organized.